Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the annotations, it discloses important behavior: same-trip/no-transfer results, ET times, and that nj_bus is scheduled only in v1.2. It does not explain limit/pagination behavior or how to resolve station identifiers, but the annotations already cover the safety profile.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loaded with the core purpose. Each sentence adds practical detail about same-trip behavior, return fields, time zone, and system options without waste.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present, the description does not need to fully document return fields, though it helpfully summarizes them. It is nearly complete for invocation, but it omits guidance on station identifier format and the limit parameter.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description carries the burden. It adds useful meaning for system values and defaults and implies that origin/destination are stations, but it leaves the limit parameter entirely unexplained and gives no station identifier format.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific resource and operation: next NJ Transit trains/buses from origin to destination on the same trip, with no transfers. It is clear enough to distinguish from a generic departures tool, but it does not explicitly name or contrast with the sibling next_departures.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives clear usage context: same-trip only, no transfers, and bus results are scheduled only in v1.2. It does not explicitly route the agent to alternatives such as next_departures or search_stations, so it stops short of full when/when-not guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.